By Michael B.
In the third law of motion, Sir Isaac Newton states that for every action force there is an equal and opposite reaction force. This means if you apply a force an equal but opposite which allows it to move. An example of this is when you push on a wall with 5N of force then the wall will push back with 5N. Another example is that when you stand up your body pushes down on the earth with 70N(your weight) and the ground pushes back up with the same amount of force. The force you apply is called the action force and the equal and oppposite force is called the reaction force. This group of forces is called an interaction pair.
In this picture, I push down on the ground and the ground pushes back up on me.
